In all cases in which micrometastasis was found, it was only present in one of the lymph nodes examined, whereas isolated tumor cells were found in up to five nodes from one patient. Cases with such findings are mainly breast and colon cancers (pN0 i+ in colorectal carcinomas: n = 39, breast: n = 25, other entities together: n = 19; micrometastasis (pN1 mi): colorectal carcinoma: n = 3, breast: n = 5, other entities together: n = 5).

While the meaning of micrometastasis in axillary lymph nodes is undebated and thus integrated in the TNM system, the prognostic value of this finding for other entities remains unclear. However, the WHO suggests a classification scheme for these.

We will now start to collect follow-up results for all patients in this study to conclude how to deal with these findings in future.